Re: [Boost-users] Lookbehind assertions problem with 1.33

I'm trying to use lookbehind assertions, and here's a problem: the following syntax

(?<=^.{2}).{4}

gives me the error:

'(?<=^.{2}).{4}' is a bad regular expression: Unmatched [ or [^

while the following works:

(?<=^..).{4}

matching, as I expected, 4 characters after the first 2 characters in a line.

Shouldn't the above two regexes work the same way?

Probably, but the lookbehind assertion code is pretty dumb at present: it needs to be able to figure out exactly how many characters to look behind in advance, and currently bounded repeats aren't supported. It's probably not too hard to support that case, but it's too late for 1.33 I'm afraid. John.